Magnetron sputtering technique is a common technology for depositing a thin film, and plays an important role in the preparation procedure of a liquid-crystal display (LCD).
FIG. 1 and FIG. 2 are structural schematic views of two types of typical magnetron sputtering apparatus in the related technology, each of the magnetron sputtering apparatus includes a deposition chamber 1, in which are oppositely provided a target and a substrate mount 3, and on the substrate mount 3 is placed a substrate 4 to be deposited with a thin film. The difference is in that the magnetron sputtering apparatus in FIG. 1 adopts a planar target 22, while the magnetron sputtering apparatus in FIG. 2 adopts a rotational target 21. Each target and the substrate mount 3 form a cathode and an anode respectively, between which an electric field and a magnetic field can be formed. On a wall of the deposition chamber 1 is provided with a gas inlet (Gas In) 5 and a gas suction outlet 6; the gas inlet 5 is used to feed working gas such as argon or the like into the deposition chamber 1, and the gas suction outlet 6 is connected to an air suction pump so as to suck out the gas in the deposition chamber 1, in order to maintain the vacuum degree as well as to circulate and replace the working gas.
The operational principle of the magnetron sputtering apparatus is explained as follows. Electrons are accelerated to fly to the substrate under the action of the electric field and collide with argon atoms during this process so as to ionize to produce a large number of argon ions and electrons, which form a plasma area 13 between the target and the substrate. The argon ions are accelerated to bombard the target under the action of the electric field, sputtering out a large number of target atoms or molecules; the target atoms or molecules which are neutral are deposited on the substrate to form a film. In order to enable more argon ions to bombard the target so as to produce more target atoms or molecules, it is necessary to improve the collision frequency between the electrons and the argon atoms. In the process of the accelerated flight to the substrate of secondary electrons, because of the magnetic field formed near the target, the secondary electrons are confined within the plasma area 13 near the target under the effect of the Lorentz force of the magnetic field, and move around the target, increasing movement paths of the electrons, and thus improving the collision frequency between the electrons and the argon atoms, so that a large number of the argon ions produced by ionization can bombard out even more target atoms or molecules.
Under the effect of the distribution of the magnetic lines of the magnetic field, the formation of the argon ions is not uniform, resulting in a non-uniform consumption of material caused by the bombard of the target surface. The apparatus as shown in FIG. 1 adopts a stationary planar target 22, which will cause a situation in which the materials in partial positions have been depleted, while other positions have a lot of materials left. The non-uniformity of the surface materials of the planar target 22 directly causes the uniformity of the film formation to be poor. If the target is replaced at this point, it leads to a waste of material. The apparatus as shown in FIG. 2 adopts a plurality of rotational targets 21, and thus can replace the rotational target 21, the material of which hays been consumed up alone, so as to ensure a provision of targets with high uniformity in the deposition chamber 1.
Nevertheless, the existing rotational targets still have some defects. At the time of the target replacement, it is necessary to stop the magnetron sputtering depositing operation, the vacuum environment in the deposition chamber will be destroyed because of the target replacement, and it is necessary to conduct a vacuuming operation and charge working gas again after the target replacement. Thus, the magnetron sputtering apparatus which adopts the rotational targets in the related technology has the defects that target replacement is difficult, and the operation cost is high.